The present invention relates to an opening and closing chuck, which is attached to an industrial robot arm or the like, and is used for the grasping (holding) of a workpiece.
Conventionally, an opening and closing chuck having the following construction has been known as an opening and closing chuck, which is attached to an industrial robot arm or the like, and is used for the grasping of a workpiece. More specifically, the opening and closing chuck includes a pair of cylinder mechanisms, a pair of chuck members, a pinion, and one guide rail. The pair of cylinder mechanisms is located in a chuck body in parallel with each other, and the pair of chuck members is driven so as to open and close by each piston of the cylinder mechanisms. The pinion engages with a rack provided on the pair of pistons so as to synchronize their piston operation, and the guide rail is incorporated into a side where the pair of chuck members of the chuck body is arranged, in order to guide the chuck members. The pair of chuck members is opened and closed in parallel with a driving direction of the cylinder mechanisms.
In the case of attaching this type of opening and closing chuck to a support body such as a robot arm or the like, in general, the following manner is done. More specifically, a plurality of stationary holes are formed in the chuck body from the side where the pair of chuck members of the chuck body is arranged toward an attaching side opposite to there, and a fixation screw is screwed into these stationary holes.
However, the center axial line of the chuck body is the most effective in stable fixation; nevertheless, usually, the pinion is arranged on the center of the chuck body, and further, places other than above are a moving range of the chuck member having a small stroke. For this reason, even if the stationary hole is formed on the position keeping away from the pinion, the chuck member is an obstacle; as a result, it is impossible to insert the fixation screw into the stationary hole. Therefore, the stationary hold must be formed on a position such that it does not overlap with a cylinder hole of each cylinder mechanism, and is positioned outside the moving range of the chuck member. After all, the stationary hole has been frequently formed on the end side of the chuck body so as to avoid the cylinder hole, the pinion, a moving space of the chuck member.
As a result, in order to secure a space for providing the stationary hole, the chuck body must be made large by the above space, and further, the opening and closing chuck is made into a large size as a whole. This is a serious problem because it is desirable to miniaturize the opening and closing chuck.
As described above, the conventional opening and closing chuck is constructed in a manner that the pair of chuck members is opened and closed in parallel with a driving direction of each cylinder mechanism by the pair of cylinder mechanisms arranged in the chuck body in parallel with each other. Therefore, the technical problem of the present invention is to prevent the chuck body from being made into a large size by securing a space required for providing a stationary hole for attaching a fixation screw, and to achieve a miniaturization of the whole of opening and closing chuck.
In order to solve the above technical problem, the present invention provides an opening and closing chuck, characterized by including: a chuck body having a first surface for fixing to a support body such as a robot arm, and a second surface opposite to the first surface; a pair of cylinder mechanisms having a pair of cylinder holes formed in the chuck body in parallel with each other, and a pair of pistons freely slidable in the cylinder holes, the pair of pistons being moved to a direction opposite to each other by a reaction of fluid pressure; a pinion engaging with a rack provided in the pair of pistons, and synchronizing an operation of the pistons by its rotation; a guide rail positioned on the center portion of the second surface of the chuck body and extending along a moving direction of the pistons; a pair of chuck members arranged so as to be freely movable along the guide rail in a state of riding on the guide rail at a relative position on the second surface, and moving to a direction opposite to each other in association with the pistons; a stationary hole formed so as to communicate with the first surface penetrating through the guide rail and the chuck body at a position covered by the chuck members of the guide rail, in order to fix the chuck body to the support body by using a screw; and a work hole formed so as to be aligned with the stationary hole on a specified moving position of the chuck member at a portion covering the guide rail of the chuck member, in order to attach a screw to the stationary hole via the chuck member.
In the opening and closing chuck having the above construction, the stationary holes are formed at a position covered by the chuck members on the guide rail, further, each chuck member is provided with a work hole, and thereby, a screw can be inserted into the stationary hole via each chuck member. Therefore, there is no need of providing a space for the stationary hole at an end portion near to the chuck body in order to avoid a moving range of the chuck members, like the conventional case. As a result, the chuck body is made into a small size by the space, so that the whole of chuck can be miniaturized.
According to the preferred embodiment of the present invention, two stationary holes and the work hole of the pair of chuck members are formed at a position symmetrical to the pinion, and these stationary holes and work holes are simultaneously aligned with each other in their hole position when the pair of chuck members is synchronously moved.
According to the preferred embodiment of the present invention, the pair of chuck members individually have a recess groove into which the guide rail is fitted, and one groove wall of one chuck member and a groove wall on the opposite side of the other chuck member are individually provided with an arm extending in parallel with the guide rail. Further, each of the arms is provided with a pin, which extends from a slot formed in a hole wall of the cylinder hole into the cylinder hole so as to be abutted against the piston, and the pair of chuck members is connected to the corresponding piston via the pin and the arm.
According to another preferred embodiment, the present invention provides the opening and closing chuck, characterized in that a plurality of steel balls constituting a linear bearing is interposed between right and left groove walls of the pair of chuck members and the guide rail so as to freely roll.